1. Field of the Invention
The present invention relates to the two-lobe and multi-lobe rotor rotary machine. More particularly, the present invention relates to the use of two or more slidably mounted seals of radial orientation located in the region of the center of the least volume portion that is formed between the rotor apexes in the housing chamber. The radial seals regulate and isolate working volumes within the machine by interaction with the periphery of the rotary piston. The advantages would apply to other epitroidal/epitrochial rotary machines and some advantages would apply to the broad class of trochoidal rotary machines.
2. Description of the Related Art
It is understood that many of the rotary piston machines represented by prior art can be used as a gas expandor. An example of this would be to power the device from high-pressure combustion gases or heated gases. In this context the rotary machine differs in function from turbo machinery or expansion of gases housed within a piston cylinder. The expandor as referred to must admit gases, from a higher pressure source that is not already contained within the volume, and convert the pressure and volume passing into the device to work. The device must then expand the gases to low pressure ideally with an isentropic expansion to extract energy from the internal energy of the gases. Henceforth, flow regulation for two-lobe or multi-lobe rotor rotary machines has represented one of the most challenging design considerations for construction of this type of machine for practical applications.
In U.S. Pat. No. 298,952, by Edwin Bryan Donkin, there is a description of the inward-bend of the cartiodal-housing fitting to the edge of the piston, this being in part trochoidal. The rotor is cut such that the surface follows a point at the inward-bend separating the inlet port and outlet port. Described also are two rotors with peripheries that follow the same point from either side and always mate together. The effect is to allow for ports of very large size whereas without this separation, the ports would be greatly restricted. This technique can also be used to internally regulate the flow such that a small port can be placed at any portion of the region of the larger ports described to provide for small expansion ratios without an external valve. The external valve similar to that described in related prior art would provide additional flow regulation to allow for much higher expansion ratios. The concept of combining the trochoidal and cartiodal design seems to originate first with this patent however radially mounted seals were not well understood. A largely stationary seal in the position described by Donkin would not have a consideration of a wide variation of pressure angles and total travel that would exist for other regions of the housing and rotor. The slidably mounted seal relaxes the geometric constraint if the seal is of such a construction so as to be allowed to adjust for relative movement of the rotor periphery at the point of contact. Positions far removed from this portion of the radial housing do not lend themselves to the use of the slidably mounted seals in general because of excessive total travel and pressure angles. Positions nearer the region of the point contact described in this prior art, however, could accommodate a reciprocating slidably mounted seal. The slidably mounted seal to separate the high pressure port from the low pressure port has not been described for epitroidal configurations relying on rotor apexes to separate working volumes.
Flow regulation by means of an external valve is described for example in U.S. Pat. No. 3,800,760 which also benefits from internal flow regulation by a rocking seal at the tip of the rotor which seals between the two working chambers as they pass over the inlet port and outlet port.
U.S. Pat. No. 4,345,886 refers to a compressor design with vanes in the housing that relies on vanes that reciprocate sliding in vane grooves. The radially inner end of each vane contacts the outer peripheral surface. This patent additionally showed ports could be placed within the rotor and the vanes can act as a valve by passing over these ports.
Similarly, U.S. Pat. No. 3,966,370 describes a rotor with a coordinated design that has minimal vane movement and uses troughs and passages to the rotor center.
U.S. Pat. No. 3,938,919 presents the use of trough shaped recesses in the peripheral piston surface to transfer gases form one working volume of a rotary machine to another.
An improvement in flow regulation of significance for this type of rotary machine would be for the use of a single stage for a compressor or expandor that allows for much larger volumetric ratios. Additionally, a method of displacing the gases contained within the minimum volume region or deriving power from this region with or without an external valve or production of torque at the top dead center position has not been adequately achieved for this type of rotary machine.